Instant Live has begun to offer Windows Media Audio (WMA) downloads of live concerts that it records and mixes in stereo-compatible SRS Circle Surround II, a 5.1-channel matrix technology that can be decoded by home and car stereo systems incorporating Circle Surround II matrix decoders or other-format matrix decoders, the company said. The songs, available on instantlive.com, play in 5.1 when burned to a CD or streamed directly from an MP3 portable connected to a home or car stereo system. Some of the songs became available on the Napster download site in late 2005, SRS Labs said.

Headphone portables will deliver the multichannel effect through stereo headphones with the addition of an SRS TruSurround XT "virtual-surround" adapter due sometime in 2006 from Imagine-It-Concepts of Huntington Beach, Calif., SRS said. The 1.2x2.2x0.75-inch adapter plugs into any audio device with a 3.5 mm headphone jack. Its internal rechargeable lithium ion battery provides 8-9 hours of use. Eventually, SRS hopes to entice makers of headphone stereos to build in TruSurround XT.

Instant Live, a division of Live nation in Los Angeles, records concerts and sells recordings of the concert on site at the end of the performance. It also sells the CDs on-line and through artist sites. Later this year, Music Giants plans to launch multichannel downloads to PCs and to HDD music servers sold through custom-A/V installers. Last year, Music Giants launched high-fidelity stereo downloads in the Windows Media Audio (WMA) Lossless format, which uses a variable-bitrate encoder to compress music files by up to 50 percent and decompress the files with bit-for-bit accuracy.

Multiple digital audio and A/V portables that support Windows Media 9 are capable of playing back MusicGiants stereo downloads. With a three-minute song requiring about 12MB of storage space, more than 1,600 songs could be stored on a 20GB portable.